Obtained by ABC News

Eighty inmates involved in an Arizona prison riot have been moved to other institutions, officials said today.

Two inmates remained hospitalized after the Sunday morning brawl that involved up to 400 inmates. Another 15 inmates were released from the prison hospital after being treated for their injuries.

The Whetstone Unit of the Arizona State Prison Complex in Tucson remained on lockdown today as authorities investigated the cause of the riot in the minimum custody unit.

"We're still investigating, doing interviews. It's going to take a little bit to get to the bottom of what started the fight," State Department of Corrections spokesman Bill Lamoreaux said.

Two staff members suffered minor injuries while breaking up the skirmish, however it was quickly contained, Lamoreaux said.

He did not know the extent of the inmates' injuries, however he told ABCNews.com the two who remain in the hospital are listed in stable condition.

The Whetstone Unit has the capacity to house 1,250 inmates and was just a few shy of being full at the time of the fight.